Pendenza del tetto: angolo, percentuale e dislivello

Dal dislivello e dalla distanza orizzontale, calcola angolo, pendenza percentuale e del tetto (x su 12), lunghezza inclinata e fattore del puntone.

Aggiornato Esempi verificati: 8

Negative for a downhill slope
Prova
Angolo
°
Angolo: 26.5651 °
Massimo di cifre decimali: 4; Al più vicino; a parità lontano da zero
Voto
50%
Roof pitch
6in 12
Ratio (rise : run)
1 : 2
Rise per unit of run
0.5
Rafter length factor
1.118034
Slope length
13.4164cm

This slope rises 0.5 for every 1 of run: 26.57° from horizontal, a 50 % grade, or a 6/12 roof pitch. Its sloped length is 13.4164 cm.

Slope profile, to scale

run 12 cmrise 6 cm26.57°6/12 pitch · 50 %
Come si calcola S
  1. Slope

    m=riserun=612=0.5m = \frac{\text{rise}}{\text{run}} = \frac{6}{12} = 0.5
  2. Angolo

    θ=arctan⁡m=arctan⁡0.5=26.565051∘\theta = \arctan m = \arctan 0.5 = 26.565051^\circ
  3. Grade and pitch

    grade=100m=50 %,pitch=12m=6 in 12\text{grade} = 100m = 50\,\%,\qquad \text{pitch} = 12m = 6 \text{ in } 12
  4. Rafter factor

    1+m2=1+0.52=1.118034\sqrt{1 + m^2} = \sqrt{1 + 0.5^2} = 1.118034

    Multiply a horizontal run by this to get the sloped length.

  5. Slope length

    rise2+run2=12×1.118034=13.416408 cm\sqrt{\text{rise}^2 + \text{run}^2} = 12 \times 1.118034 = 13.416408\,\text{cm}

Informazioni su Pendenza del tetto: angolo, percentuale e dislivello

Every way of stating a slope comes from one ratio, m = rise ÷ run. The angle from horizontal is arctan m, the percent grade is 100m, the roof pitch is 12m (units of rise per 12 of run), and the rafter factor √(1 + m²) turns a horizontal run into the sloped length. Enter a rise and run, or any one of the other forms, and the rest follow.

The default rise of 6 over a run of 12 is a 6/12 roof: 26.57°, a 50% grade and a rafter factor of 1.1180, so 12 cm of run needs 13.4164 cm of rafter. Ramps and roads use the same numbers: the steepest ramp the 2010 ADA Standards allow, 1:12, is an 8.33% grade, or 4.76°.

Percent grade is not an angle: a 100% grade is 45°, and a vertical face has no finite grade or pitch, so angles must lie between −90° and 90°. A negative rise describes a downhill slope.

Esempi svolti

Rise 6, run 12 (a 6/12 roof)

Misura nota
Rise and run
Rise
6 cm
Run (horizontal distance)
12 cm
Unità dei risultati
Centimetri (cm)
Angolo
26.565051 °
Voto
50%
Roof pitch
6 in 12
Ratio (rise : run)
1 : 2
Rafter length factor
1.118034
Slope length
13.416408 cm

Fonte di verifica: Python 3.8 math: degrees(atan(0.5)), sqrt(1.25), sqrt(6**2 + 12**2)

45°

Misura nota
Angolo
Angle from horizontal
45 °
Voto
100%
Roof pitch
12 in 12
Ratio (rise : run)
1 : 1
Rafter length factor
1.414214

Fonte di verifica: tan 45° = 1; Python 3.8 math.sqrt(2)

8 % road grade

Misura nota
Percent grade
Voto
8%
Angolo
4.573921 °
Roof pitch
0.96 in 12
Ratio (rise : run)
1 : 12.5

Fonte di verifica: Python 3.8 math: degrees(atan(0.08)); 12 × 0.08; 1/0.08

4/12 roof pitch

Misura nota
Roof pitch
Pitch
4 in 12
Angolo
18.434949 °
Voto
33.333333%
Rafter length factor
1.054093

Fonte di verifica: Python 3.8 math: degrees(atan(4/12)), sqrt(1 + 1/9)

Domande

How do you convert percent grade to degrees?

Take the arctangent of the grade divided by 100: θ = arctan(grade/100). An 8% road grade is arctan 0.08 = 4.57°, and a 100% grade is 45°, not 90°. The reverse is grade = 100 × tan θ, so a 30° slope is a 57.7% grade.

What angle is a 6/12 roof pitch?

26.57°. A pitch of x/12 means x units of rise for every 12 of run, so the angle is arctan(x/12): 4/12 is 18.43°, 6/12 is 26.57°, 8/12 is 33.69° and 12/12 is 45°. The rafter factor for 6/12 is √1.25 = 1.118, so 12 ft of horizontal run needs 13.42 ft of rafter before any overhang.

What is the maximum slope for a wheelchair ramp?

1:12 under the 2010 ADA Standards for Accessible Design (§405.2): one unit of rise for every 12 of run, an 8.33% grade or 4.76°. Each ramp run may rise at most 30 in (§405.6), so a 30 in rise needs a run of at least 30 ft. Other countries set their own limits in their building codes.

How do you calculate rise over run?

Divide the vertical rise by the horizontal run, both in the same unit: m = rise/run. A roof that rises 6 in over 12 in of run has m = 0.5. Measure the run horizontally, not along the surface: the sloped length here is 13.42 in, and dividing by it gives 0.447, the sine of the angle rather than the slope.

Quanto è preciso «Pendenza del tetto: angolo, percentuale e dislivello»?

La precisione dipende dai dati inseriti e dalle ipotesi del metodo. Il calcolo decimale usa 50 cifre significative, ma stime, metodi numerici e dati di origine possono essere meno precisi; l’arrotondamento visualizzato non elimina questi limiti. Esempi svolti verificati con fonti indipendenti: 8. Per esempio, «Rise 6, run 12 (a 6/12 roof)» viene verificato con Python 3.8 math: degrees(atan(0.5)), sqrt(1.25), sqrt(6**2 + 12**2).

Da dove proviene il metodo?

OpenStax College Algebra 2e, §4.1 — slope as rise over run; US Access Board, ADA Standards §405.2 — ramp slope 1:12 (8.33 %).

Informazioni su questa calcolatrice

m=riserun,θ=arctan⁡m,grade=100m %pitch=12m in 12,factor=1+m2\begin{gathered} m = \frac{\text{rise}}{\text{run}},\quad \theta = \arctan m,\quad \text{grade} = 100m\,\% \\[6pt] \text{pitch} = 12m \text{ in } 12,\quad \text{factor} = \sqrt{1 + m^2} \end{gathered}

Fonti

  1. OpenStax College Algebra 2e, §4.1 — slope as rise over run
  2. US Access Board, ADA Standards §405.2 — ramp slope 1:12 (8.33 %)

Verificato con le fonti

Questa calcolatrice include 8 esempi svolti con risposte da fonti indipendenti. Fanno parte della suite di test e puoi eseguirli anche qui.

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